New research identifying a nutrient combination that claims to slow the progression of Alzheimer’s disease (AD) has been criticised by the scientific community, who urged caution over the study’s conclusions.

The 18-month study, examining the effect of macular carotenoids lutein, meso-zeaxanthin, zeaxanthin and omega-3 fatty acids on patients with AD commented on the “positive outcomes​”, setting up the prospect of similar findings in future work.

“I believe this research paves the way for potential prevention of AD,” ​said Dr Alan Howard, study researcher and founder and chair of the Howard Foundation.

“Due to the small scale of this initial trial, we’ve now funded a larger project to confirm these findings. But it would be negligent for us to ignore these results until the next study reports back, which will take several years.”​

Breakthrough claims ‘irresponsible’​

However, the small sample size along with the study design was the source of criticism from fellow researchers, who dismissed the “breakthrough” ​claims as irresponsible.

“This report is sadly not much more than low-grade anecdotal evidence,”​ said Robert Howard, professor of old age psychiatry at University College London.

“Certainly, it falls seriously short of the standards of a high quality clinical trial in terms of scale and conduct. ​

“The accompanying claims made by Dr Howard seem irresponsible and completely unsupported by any reasonable reading of his data. ​

“Sadly, people with dementia and their carers will grasp at any straw and I would worry about the impact of media reports around what seem either naive or deeply cynical attempts to exploit this.”​

Study design​

Performed by a team at the Nutrition Research Centre Ireland (NRCI) in collaboration with University Hospital Waterford (UHW), the work initially set out to examine the biochemical response of AD patients to two different combinations of nutritional supplements.

Three trial experiments were carried out. In trials one, 12 patients were supplemented with a xanthophyll carotenoid only formulation (lutein:meso-zeaxanthin: zeaxanthin 10:10:2 milligrams per day (mg/day)).

In trial three, the control group, 15 subjects free of AD were supplemented for six months with formulation one.

The team measured blood xanthophyll carotenoid response in all trials by high-performance liquid chromatography (HPLC).

Results found xanthophyll carotenoid concentration increases were significantly greater for formulation two compared to formulation one and progression of AD was less for this group with carers reporting functional benefits in memory, sight, and mood.

“This preliminary report suggests positive outcomes for patients with AD who consumed a combination of xanthophyll carotenoids plus fish oil,”​ the study concluded. “Further study is required to confirm this important observation.”​

Placebo control lacking​

But Naveed Sattar, professor of metabolic medicine at the University of Glasgow, responded to the study findings with scepticism arguing that a lack of a control harmed the work’s validity.

“Whilst any research in Alzheimer’s disease is to be welcomed, this is too small a trial and lacks a placebo control so that its findings are highly unlikely to true. ​

“In fact I would place no reliance on these results, especially since we know little effect of fish oils or carotenoid supplements on other outcomes in proper trials.”​

Dr Sujoy Mukherjee, consultant psychiatrist (old age), West London MH NHS Trust, commented that the key finding in the study was that a combination of nutrients was superior to an individual one was important.

“There is certainly a need to conduct large scale research in the role of nutritional supplements in both prevention and management of AD.”​

Researcher response ​

Responding to the criticism Professor John Nolan, founder of the NRCI, who led the study, highlighted​​ that the study included 27 patients in total, including two comparison groups who were given macular carotenoids only.

"We greatly appreciate the review and commentary of our scientific peers,”​ he said.

"This study acknowledges that the results were unexpected, and the research was not designed specifically to evaluate functional and cognitive outcomes.​